Rear tire width requirements in relation to HP?

I was just wondering, I have seen several Mopars on here with HUGE motors and yet tiny rear tires...

How does that work??? Don't they just burn like crazy, and verge on dangerous in general around town?

In this light then, what is the balance? I have a pretty bad to the bone 383 my Dad built being put in my '70 Dart in the next couple weeks, and the rear 15x8 wheels have 255/60/r15's on them...

I felt like this was the minimum size when ordering them, (although, since it has the springs relocated some, with a bit more backspace I could go 275's looks like)...

So, am I way off base here??? With all the sweet parts going into these cars, like hardcore cams, head set ups, carbs, etc, how is it many of these have such tippy-toe tires???

(serious question, I have never built a Mo before, just drove stock 318's around)